i am facing these weird problems in ubuntu 8.04.

My system is on a LAN comprising of about 18 computers(all Windows), of which 5 have internet connection which have been shared.
I recently shifted over from windows were the common habit was to just change my default gateway to the ip of the comp on LAN i want to take internet connection of and then just simply surf the net.

But ubuntu...well...the thing is 6 out of 10 times the system will automatically get the net connection with roaming mode enabled and then sometimes for no reason at all it refuses to. I then tried static ip addressing and gave a default gateway it didint work...then after few more tries static ip worked...i have tried a lot of variations with no consistency, generally roaming mode works.

I would really like to know

1. What roaming mode really does, how is it different from DHCP and IP
2. How to get my internet working because i dont face the above problems in windows

Also sometimes computers on LAN are accessible and then mostly not(ié through Places->Network)

Thanks for your help

PS i have just switched over from windows but access to internet is proving to be troublesome